New Delhi, May 20 -- The mental well-being of three elephants in a zoo in South Africa is the subject of an unusual court case, with animal welfare groups saying they are depressed and should be moved to a larger conservation park where they can be happy.

The case this week will ask a South African court to decide if the state is meeting its legal obligations with regard to the welfare of the animals and the conditions in which they are kept, according to David Bilchitz, a board member at Animal Law Reform South Africa, one of the groups bringing the case.

Experts would show in court that the elephants are unhappy, Bilchitz said. The animal welfare groups said a part of the South African Constitution puts an obligation on authorities to...